Best practices - Way direction?


I am new to the OSM community and have been using OSM data for a hydrological model covering the Murray Darling Basin, Australia.

As a result I am using OSM’s river centerlines, whilst adapting these for my purposes, I noticed that there was little consistency in the direction of the ways. I.e. first point in the way being the most upstream and the last point being the most downstream (following the direction of water flow). I am not sure if there is a best practice that defines how these ways should be entered.

Regardless, I have written an algorithm to use a DEM and correct the line directions for my personal uses, would it be valuable to contribute these ways with consistent direction back to the OSM DB? Is this a known best practice or is it not important in the world of mapping?

Thanks for the advice :slight_smile:

If I understand your question, you’re asking whether you can correct the direction of flow on certain waterways.

It is absolutely correct to change those way directions if you have data to confirm your edits. How the way was drawn originally is not important because one can reverse the direction of any way easily. What’s important is that the direction of the way follows the flow of the river from higher ground to low.

Another point I’ll make based on my own experience as an armchair mapper, is that the direction of flow of a waterway isn’t always obvious. In such cases, I’ll include a note on the waterways I map saying that the actual direction of flow is unknown. This allows someone who knows more than I do to feel free to change the direction later.

Naturally, any such corrections would be useful for OSM and welcome.

Hi and welcome to OSM and the forum

You are right. Direction for waterways is important as defined in our Wiki:

There is an QA tool for identifying such issues OSM Inspector

Thanks all! I will look into contributing the changes when I can. :slight_smile: